1. Technical Field
The present invention relates to a transflective liquid crystal display device, which has a reflective mode and a transmissive mode, and an electronic apparatus. More specifically, it relates to a structure of a so-called mono/color liquid crystal display device in which the reflective mode is operated for black-and-white display and the transmissive mode is operated for color display.
2. Related Art
In recent years, as display devices for cellular phones or PDAs, transflective liquid crystal display devices which have a reflective mode and a transmissive mode are widely used. In such transflective liquid crystal display devices, a reflecting film made of a metal film such as aluminum or the like and having a slit (opening portion) therein for light transmission is provided on an inner surface of a lower substrate, such that the reflecting film serves as a transflective film. In this case, in the reflective mode, external light incident from an upper substrate is reflected at the reflecting film disposed on the inner surface of the lower substrate after passing through a liquid crystal layer, passes back through the liquid crystal layer, and is emitted from the upper substrate for display. On the other hand, in the transmissive mode, light from a backlight incident from the lower substrate passes through the liquid crystal layer through the opening portion of the reflecting film and is emitted from the upper substrate to the outside for display. Therefore, the region of the reflecting film with the opening portion is a transmissive display region and the other region is a reflective display region (see Japanese Unexamined Patent Application Publication No. 2003-172924).
In a widely used transflective liquid crystal display device, a color filter is provided on any one of the upper substrate and the lower substrate. For example, in Japanese Unexamined Patent Application Publication No. 2003-172924, a transflective liquid crystal display device in which the reflecting film and the color filter are sequentially laminated on the inner surface of the lower substrate, and the reflective mode and the transmissive mode are operated for color display is disclosed. However, according to the use, the reflective mode may be operated for black-and-white display, not for the color display, for the sake of brightness. Accordingly, the inventors have proposed a liquid crystal display device in which a color filter is provided on only the transmissive display region (the opening portion of the reflecting film), earlier than the present invention. Hereinafter, such a transflective liquid crystal display device is referred to as a mono/color liquid crystal display device.
FIG. 9B is a schematic view showing a cross-sectional structure of the lower substrate of the mono/color liquid crystal display device proposed previously. In the liquid crystal display device, a reflecting film, the color filters (colored layers) R, G, and B, a planarizing film, and a transparent electrode are sequentially laminated on the lower substrate. In the reflecting film, the opening portion is provided at a central portion of each pixel. The region with the opening portion (transmissive portion) is the transmissive display region and the other region is the reflective display region. The colored layers R, G, and B are selectively formed in only the opening portions of the reflecting film serving as the transmissive display regions.
In the transflective liquid crystal display device, in order to obtain brightness at the time of the reflective display, the reflective display region is formed wider than the transmissive display region. In the mono/color liquid crystal display device, the reflective display region is widened and thus the occupied area ratios of the colored layers R, G, and B on the substrate become small. In a plan view, the intervals of the adjacent colored layers R, G, and B become extremely large as compared to the sizes of the colored layers R, G, and B. For this reason, when the colored layers R, G, and B are formed thicker for the purpose of increasing color purity, unevenness due to the colored layers is not sufficiently planarized by the planarizing film, which results in gap irregularity. In particular, when gap control needs to be performed with high precision, as in a STN-type liquid crystal display device or the like, such gap irregularity causes the display quality to be significantly degraded. In order to solve these problems, the inventors have proposed a structure in which a black matrix BM is arranged on a portion of a region where the colored layer is not formed, as shown in FIG. 9A. In this case, since a space between the colored layers is partially covered with the black matrix BM, planarization of the substrate surface is enhanced as compared to the above-described structure. In this structure, however, since the black matrix BM is formed in the reflective display region, the reflective display darkens. Further, in the above-described structures, if a positional deviation occurs between the opening pattern of the reflecting film and the pattern of the colored layer, reflective luminance and transmissive luminance are degraded. Accordingly, there is a problem in that the formation of the pattern needs to be performed with high precision.